Answer:
Has its teeth on your head but doesn't bite
Everyone claims to know a way to stop these involuntary contractions but none of them work.
A first job for many kids, this could be described as "Media Distribution Management.
What do you call a teacher with no arms, no legs and no body?
What belongs to you but others use it more than you do?
A hole in a pole, though I fill a hole in white. I'm used more by the day, and less by the night.